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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 26 |
| 6 | 124 |
| 7 | 628 |
| 8 | 3565 |
| 9 | 22096 |
| 10 | 149176 |
| 11 | 1080868 |
| 12 | 8372543 |
| 13 | 68957268 |
| 14 | 601351748 |
| 15 | 5528967282 |
| 16 | 53416626441 |
| 17 | 540682811424 |
| 18 | 5718911631856 |
| 19 | 63060992662328 |
| 20 | 723382253378395 |
| 21 | 8616075340134868 |
| 22 | 106374847828850676 |
| 23 | 1359171823319541070 |
| 24 | 17946987240664242493 |
[1,0,1,2,7,26,124,628,3565,22096,149176,1080868, 8372543,68957268,601351748,5528967282,53416626441, 540682811424,5718911631856,63060992662328, 723382253378395,8616075340134868, 106374847828850676,1359171823319541070, 17946987240664242493] |